It's obsolete. It was obsolete for how war was actually fought in the 1940s the same way it is obsolete for how war is fought now. Its strength was that, while it was still not optimized for real combat, it was better than its contemporaries like the SMLE and Kar-98K.
I think that just because the role of the Garand isn't being used by any modern military doesn't mean that it's not a viable role anymore. With the right tactics, I think that an army of Garand-wielding soldiers can be just as formidable as any assault rifle-armed military.
It's a popular myth that before that evil old McNamara forced poodle shooters on the US military we were all stone-faced, steely-eyed riflemen picking off the Hun or Japs at a thousand yards with our precision rifle fire.
It's also utter nonsense.
We went into WW2 with a flawed tactical doctrine that stressed long range rifle fire because a bunch of very silly generals failed to grasp that when a guy is dressed in something the color of mud and doing his best to be a minimal target he's just not going to be acquired, much less hit, at anything beyond rather close range. Troops got into combat and found that just because you could pop a round bullseye across a carefully manicured range there was no reason to think you could hit real targets at the same ranges.
A lot of guys lost their lives or were crippled and maimed learning that the training they'd gotten stateside was just shoddy when the rubber met the road on the two-way shooting range, and many veterans of WW2 have discussed how they had to deprogram all that manicured lawn NRA target shooting out of replacement personnel and get them properly trained to suppress, fire, and manuever to close with the enemy and bring real-world effective fire on him, etc.
WW2 is the war the provided us the "almost all infantry engagements occur within 300 meters" factoid after study of how real combat took place. A lot of people had already realized this prior to WW2 (the US, Germans, and Russians were all pushing towards an intermediate round, assault rifle-ish sort of weapon before WW2), but WW2 made the handwriting on the wall
almost impossible to ignore (but the US Army managed to do so with the M14 and 7.62x51, at least until the next round of real combat forced the issue).
Combat weapons since that war have not reflected a change in tactical doctrine. They have represented increasing optimization of the service rifle/carbine to actual combat conditions, based on real study of the environment rather than acceptance of conventional wisdom, wishful thinking, and mythology.
All that said, the Garand was a great weapon for its time, because while it was not ideal for real combat conditions (even at the time it was fielded) it was much better for it than most of its contemporaries (the StG-44 and, maybe, FG-42 being exceptions). I wouldn't want to go downrange with a Garand today, even though I like them enough to own two of them (and probably would have taken one in 1941 given the existing options), the same way I would not want to go downrange with a Spencer lever gun today, either, but would have taken one over the alternatives if I was marching or riding into Gettysburg on the 1st of July, 1863. Both will kill someone deader than cancer, there are just better ways to do it today.
And yes, the .276 Pederson (it's magnum class), would be better, but it doesn't exist anymore.
If you know of a virtual duplicate of the .276 Pederson, then that's what I'd want the ideal Garand to be chambered for.
From Barnes'
Cartridges of the World -- 276 Pedersen is listed as either a 120 grain bullet at 2550 fps for 1732 foot-pounds or 150 grain bullet at 2360 for 1858 foot-pounds. 6.8mm Remington SPC (115 grain loading from Remington, guessing 20" barrel) is 2800 fps for 2002 foot-pounds. 6.5mm Grendel (123 grain Lapua scenar, 19.5" barrel) is 2565 fps for 1797 foot-pounds. Either one basically does what they were looking at for .276 Pedersen (as do the British 280 and 280/30 rounds, for that matter).